mlxsw: spectrum_flower: Forbid to offload mirred redirect on egress

Spectrum ASIC does not support redirection on egress, so refuse to
insert such flows:

$ tc qdisc add dev ens16np1 clsact
$ tc filter add dev ens16np1 egress protocol all pref 1 handle 101 flower skip_sw action mirred egress redirect dev ens16np2
Error: mlxsw_spectrum: Redirect action is not supported on egress.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>